How Earth’s changing ecosystems may have driven human evolution

The most detailed ever look at Earth’s prehistoric climate suggests many habitats changed in the past 800,000 years – and this may be why we evolved big brains

East Africa’s unstable ecosystems may have driven human evolution

Ralph Lee Hopkins/national geographic image collection

By Michael Marshall

FOR the first time, we have had a detailed look at how our climate has changed throughout prehistory, thanks to a surprisingly detailed computer model. And it could shed light on how ecosystem changes shaped our evolution and intelligence.

Thanks to ice cores and other natural records, we already knew that, for the past 2.5 million years, Earth has been in an ice age, with permanent ice at both poles. The extent of this ice has often waxed and waned during this …